The invention pertains to methods of etching insulative materials, and in particular embodiments pertains to methods of forming electrical devices, such as, for example, methods of forming capacitors.
Semiconductor device fabrication frequently comprises removal of materials by etching. Etching methods can be divided into three general categories. A first category comprises so-called chemical etching, wherein an etchant gas chemically reacts with a material which is to be removed to convert such material to a form which can be readily removed. Another type of etching is so-called physical etching, wherein a material is bombarded with particles which displace the material. The bombarding particles are non-reactive with the material, and accordingly displace the material through purely physical interactions. Such physical etchant processes are sometimes referred to as xe2x80x9cion-millingxe2x80x9d. The third category of etching comprises a combination of physical and chemical etching. An etching gas is provided which comprises some components that chemically react with the material which is to be etched to form a modified material. The gas also comprises components which are non-reactive with either the material which is to be etched or the modified material, but which displace the one or both of the material which is to be etched and the modified material through physical interactions.
It is noted that any one of the three categories of etching processes discussed above (i.e., the chemical, physical, or combined chemical/physical processes) can be conducted in the presence of plasma, and that the physical etches are typically conducted in the presence of plasma.
In another aspect of the prior art, a number of materials have been introduced for semiconductor electronic device fabrication which are difficult to etch with anything but physical etch processes. Such materials include, for example, platinum and palladium. Platinum and palladium have been used for, for example, electrodes in capacitor constructions. Other materials utilized in capacitor constructions are dielectric materials, such as, for example, silicon dioxide, silicon nitride tantalum pentoxide, barium strontium oxide, and strontium bismuth tantalate. Dielectric materials can be, for example, chosen from the group consisting of Ba(1xe2x88x92x)SrxO3, PbZr(1xe2x88x92x)TixO3, PZT with various dopants such as LA etc., Sr(1xe2x88x92x)BixTaO3, Sr(1xe2x88x92x)BixTiO3 and all of the other Smolenski compounds, PbMg(1xe2x88x92x), NbxTiO3 (PMN), compounds with PbTiO3 (PMNxe2x80x94PT), CaBi2Nb2O9, SrBi2Nb2O9, BaBi2Nb2O9, PbBi2Nb2O9, BiBi2NbTiO9, BaBi4Ti4O15, CaBi2Ta2O9, SrBi2Ta2O9, BaBi2Ta2O9, PbBi2Ta2O9, Bi4Ti3O12, SrBi4Ti4O15, BaBi4Ti4O15, PbBi4Ti4O15, (Pb, Sr)Bi2Nb2O9, (Pb, Ba)Bi2Nb2O9, (Ba, Ca)Bi2Nb2O9, (Ba, Sr)Bi2Nb2O9, BaBi2Nb2O9, Ba0.75Bi2.25Ti0.25Nb1.75O9, Ba0.5Bi2.5Ti0.5Nb1.5O9, Ba0.25Bi2.75Ti0.75Nb1.25O9, Bi3TiNbO9, SrBi2Nb2O9, Sr0.8Bi2.2Ti0.2Nb1.8O9, Sr0.6Bi2.4Ti0.4Nb1.6O9, Bi3TiNbO9, PbBi2Nb2O9, Pb0.75, Bi2.25Ti0.25Nb1.75O9, Pb0.5Bi2.5Ti0.5Nb1.5O9, Pb0.25Bi2.75Ti0.75Nb1.25O9, Bi3TiNbO9, PbBi4Ti4O15, Pb0.75Bi4.25Ti3.75Ga0.25O15, Pb0.5Bi4.5Ti3.5Ga0.5O1.5, and Bi5Ti3GaO15.
Several of the dielectric materials being utilized for capacitor constructions, or being proposed for utilization in capacitor constructions, correspond to complexes of metal and oxygen, such as, for example, tantalum pentoxide, barium strontium oxide, etc. Such complexes can have advantages over more traditional materials, such as, for example, silicon dioxide or silicon nitride, in that the complexes of metal and oxygen can comprise higher dielectric constants than the traditional complexes.
Problems are occasionally encountered during etching of materials, such as, for example, during etching of metal and oxygen complexes. Accordingly, it would be desirable to develop new etching methods for utilization in semiconductor device fabrication.
In one aspect, the invention encompasses a method of etching insulative materials which comprise complexes of metal and oxygen. The insulative materials are exposed to physical etching conditions within a reaction chamber and in the presence of at least one oxygen-containing gas.
In another aspect, the invention encompasses a method of forming a capacitor. An electrically conductive first layer is formed over a substrate, and a second layer is formed over the first layer. The second layer is a dielectric layer and comprises a complex of metal and oxygen. A conductive third layer is formed over the second layer. The first, second and third layers are patterned into a capacitor construction. The patterning of the second layer comprises exposing the second layer to at least one oxygen-containing gas while also exposing the second layer to physical etching conditions.